California Code, Public Resources Code - PRC § 3326

An order requiring unit operation may be amended for good cause by a subsequent order entered by the supervisor, except that no such order or amendment shall change the percentage of oil and gas allocated to a separately owned tract by the original order except with the consent of all persons who might be adversely affected thereby.  Before issuing any such order, he shall make similar findings as are required for an original order, and such new order shall be subject to the same requirements and restrictions that are applicable to an original order.  The provisions of this section shall not prohibit the establishment of an interim formula for the apportionment and allocation of unit production pursuant to subdivision (d) of Section 3322.